Performance optimization in sqlite3BtreeCursor().

FossilOrigin-Name: ea068b099c96b8b9526114732d2a6be186cf381b7329d102778ad25b95510c9e

diff --git a/manifest b/manifest
index f9593b107f5bc502e7138e70f659be86002ee4a8..ca33b71ebdf96fe3615a36021cc17d9840639dc2 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C In\sfts5,\sfix\sa\scase\sof\soverreading\sa\sbuffer\sby\s1\sbyte\swhen\scounting\scharacters\sin\smalformed\sutf-8.\sFix\sfor\s[dd1f67bf].
-D 2019-10-24T20:35:27.749
+C Performance\soptimization\sin\ssqlite3BtreeCursor().
+D 2019-10-25T14:46:05.015
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -467,7 +467,7 @@ F src/auth.c a3d5bfdba83d25abed1013a8c7a5f204e2e29b0c25242a56bc02bb0c07bf1e06
 F src/backup.c f70077d40c08b7787bfe934e4d1da8030cb0cc57d46b345fba2294b7d1be23ab
 F src/bitvec.c 17ea48eff8ba979f1f5b04cc484c7bb2be632f33
 F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
-F src/btree.c a8a9c2ce62bdf54c8cf9795143d7cb10b7473a1230a0572f702d061ffcceefe5
+F src/btree.c 12e251f8c3eaad05e6d0db94772bf779b3a644e18d884025da6bcbc98cad1d22
 F src/btree.h f27a33c49280209a93385e218306c4ee5f46ba8d7649d2f81a7166b282232484
 F src/btreeInt.h 91806f01fd1145a9a86ba3042f25c38d8faf6002701bf5e780742cf88bcff437
 F src/build.c 0e558ef847ccc4b6aa38dee44cde9d9df46e953b0a66e4fa4376265824955fe3
@@ -1848,7 +1848,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 521f1d36282549488a47a434484a24924ee970d29f05a8ae499b7d536bcd692b
-R 0e068e9d9a1f90654b1d1392ec7133b9
-U dan
-Z de4cd0a7404bbb9013415658a762354d
+P 8d964e1c21d4cea699023e02b0616a75c5859dd083c9365cdcbc0676ebbdaae4
+R 8536c2fabd9f7098038221269ecc3472
+U drh
+Z ac1675b2b1cf8ed8d7717d3ccad9b463

diff --git a/manifest.uuid b/manifest.uuid
index 05a16eff55df1ad98d4d5930ec792091f4c20942..9f2d452b2445762a527add6a33df420ac3f91521 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-8d964e1c21d4cea699023e02b0616a75c5859dd083c9365cdcbc0676ebbdaae4
\ No newline at end of file
+ea068b099c96b8b9526114732d2a6be186cf381b7329d102778ad25b95510c9e
\ No newline at end of file

diff --git a/src/btree.c b/src/btree.c
index 2150638aee2f7870b5e3463984966afd15c1102d..b4c787edbf6c231afd44ea3579add3c4e075d013 100644 (file)
--- a/src/btree.c
+++ b/src/btree.c
@@ -4379,9 +4379,13 @@ static int btreeCursor(
     allocateTempSpace(pBt);
     if( pBt->pTmpSpace==0 ) return SQLITE_NOMEM_BKPT;
   }
-  if( iTable==1 && btreePagecount(pBt)==0 ){
-    assert( wrFlag==0 );
-    iTable = 0;
+  if( iTable<=1 ){
+    if( iTable<1 ){
+      return SQLITE_CORRUPT_BKPT;
+    }else if( btreePagecount(pBt)==0 ){
+      assert( wrFlag==0 );
+      iTable = 0;
+    }
   }
 
   /* Now that no other errors can occur, finish filling in the BtCursor
@@ -4406,6 +4410,19 @@ static int btreeCursor(
   pCur->eState = CURSOR_INVALID;
   return SQLITE_OK;
 }
+static int btreeCursorWithLock(
+  Btree *p,                              /* The btree */
+  int iTable,                            /* Root page of table to open */
+  int wrFlag,                            /* 1 to write. 0 read-only */
+  struct KeyInfo *pKeyInfo,              /* First arg to comparison function */
+  BtCursor *pCur                         /* Space for new cursor */
+){
+  int rc;
+  sqlite3BtreeEnter(p);
+  rc = btreeCursor(p, iTable, wrFlag, pKeyInfo, pCur);
+  sqlite3BtreeLeave(p);
+  return rc;
+}
 int sqlite3BtreeCursor(
   Btree *p,                                   /* The btree */
   int iTable,                                 /* Root page of table to open */
@@ -4413,15 +4430,11 @@ int sqlite3BtreeCursor(
   struct KeyInfo *pKeyInfo,                   /* First arg to xCompare() */
   BtCursor *pCur                              /* Write new cursor here */
 ){
-  int rc;
-  if( iTable<1 ){
-    rc = SQLITE_CORRUPT_BKPT;
+  if( p->sharable ){
+    return btreeCursorWithLock(p, iTable, wrFlag, pKeyInfo, pCur);
   }else{
-    sqlite3BtreeEnter(p);
-    rc = btreeCursor(p, iTable, wrFlag, pKeyInfo, pCur);
-    sqlite3BtreeLeave(p);
+    return btreeCursor(p, iTable, wrFlag, pKeyInfo, pCur);
   }
-  return rc;
 }
 
 /*